The present invention relates to a protecting device for a fail-safe purpose in case of a failure, an accident, etc. in an electromobile incorporating a synchronous motor therein as a power source.
The development of electromobiles has been rapidly progressed from the viewpoint of countermeasures against environmental problems, and the power source of an increasing number of the recent electromobiles has been replaced with an alternating current motor from a direct current motor because of its advantageous points such as maintenance easiness and the like. Particularly, a synchronous motor using a magnet as a rotor is highly efficient, and therefore eagerly fitted for use in the electromobiles. While the synchronous motor of this kind has conventionally been widely used in the factory automation or industrial field, the basic controlling system of the synchronous motor used in electromobiles is almost the same as in the factory automation or industrial usage.
However, because of the undeniable fact that human lives are exposed to a high risk in vehicles, it is necessary to take all possible fail-safe measures.